Heretofore, there have been known various image recording apparatus for forming a desired two-dimensional image on an image recording surface based on image data.
There have been proposed, as an example of image recording apparatus, exposure apparatus which employ a spatial light modulator such as a digital micromirror device (DMD) or the like for exposing a film to an image represented by a light beam that is modulated by image data. The DMD comprises a number of micromirrors disposed in a two-dimensional array in memory cells (SRAM array) on a semiconductor substrate of silicon or the like. The micromirrors have respective reflecting surfaces whose angles are changed when the micromirrors are tilted by controlling electrostatic forces due to electric charges stored in the memory cells. When the angles of the reflecting surfaces are changed, image recording dots are formed at desired positions to form an image.
An exposure apparatus employing a DMD has been proposed. The exposure apparatus forms a desired two-dimensional image on an exposure surface by moving the DMD in a predetermined direction relatively to the exposure surface and supplying image recording dot data to the memory cells of the DMD to form a chronological sequence of successive image recording dot groups with a micromirror group of the DMD (see Japanese Laid-Open Patent Publication No. 2003-50469 for details).
The micromirror group of the DMD comprises an array of micromirrors arranged in rows and columns which extend perpendicularly to each other. The DMD that is inclined to the scanning direction is effective to reduce the intervals between scanning lines for increased resolution.
Image data are usually supplied to the exposure apparatus while they are arrayed in a sequence along the direction in which the micromirrors of the DMD move relatively to the exposure surface. If the image data are read and supplied to the memory cells of the DMD in the same sequence, then since it is time-consuming to read the image data, a desired two-dimensional image cannot efficiently be recorded on the exposure surface.
For recording a two-dimensional image on the above exposure apparatus, therefore, it is necessary to convert image data representing the two-dimensional image into frame data depending on the array of the micromirrors of the DMD and then supply the frame data to the DMD.
However, it is highly burdensome for the exposure apparatus to convert image data at a time into frame data that are to be supplied to the many memory cells of the DMD.
Furthermore, image data are supplied from an external processing apparatus which is independent of the exposure apparatus. Unless the external processing apparatus and the exposure apparatus have the same data processing rate, the data processing rate of one of the apparatus tends to limit the data processing rate of the other apparatus. While efforts may be made to equalize the data processing rates of the external processing apparatus and the exposure apparatus, they make one of the apparatus suffer from a specification overkill and hence an increase in the cost.